sedimentary

Banded iron formation fragment (likely hematite–magnetite ironstone)

BIF; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica as microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Gray-brown, reddish, and silvery undulating bands with earthy to submetallic luster; typically massive and fine-grained, hardness about 5–6.5, specific gravity roughly 3.0–5.2 depending on iron content, with no obvious cleavage.

Identified August 14, 2026More sedimentary →

Explore Banded iron formation fragment (likely hematite–magnetite ironstone) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Banded iron formation fragment (likely hematite–magnetite ironstone)
Scientific name: BIF; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica as microcrystalline quartz (SiO₂)
Category: sedimentary
Identified: August 14, 2026
Method: Standard

AI Estimated Value

Common hand specimens: about $5–$30; attractive polished or strongly banded pieces: $30–$150.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Chemical sediment deposited in Precambrian marine basins, commonly 2.5–1.8 billion years old, when dissolved oceanic iron precipitated with silica during the rise of atmospheric oxygen; later compacted and metamorphosed.

Uses & applications

Major iron ore when sufficiently rich; also used as a lapidary, ornamental, and mineral-collecting material.

Geological facts

The alternating iron-rich and silica-rich layers record ancient ocean chemistry and Earth’s Great Oxidation Event; magnetite-rich pieces may attract a strong magnet.

Field identification & locations

Identify by thin, naturally repetitive banding, unusual heaviness, rusty streaks, and possible magnetism; common in Australia, Brazil, India, South Africa, Ukraine, and the Lake Superior region. The photograph alone cannot confirm BIF versus banded metamorphic ironstone.